Ubiquitin Protein Ligase E3 Component N-Recognin 4 (UBR4)

RBAF600 associates with RB in the nucleus and with Ca(2+)-bound calmodulin in the cytoplasm.p600 and RB appears to act as a chromatin scaffold, and in the cytoplasm p600 and clathrin form a meshwork structure which could contribute to cytoskeletal organization and membrane morphogenesis. Reduced expression of p600 with interfering RNA abrogated integrin-mediated ruffled membrane formation and prevented activation of integrin-mediated survival pathways. The deduced 5,183-amino acid protein has a calculated molecular mass of 573.5 kD. Immunostaining of human foreskin fibroblasts localized p600 in a continuous meshwork pattern from the nucleus to the cytoplasm, passing through the nuclear envelope. In the cytoplasm, p600 was concentrated at the leading edge of membrane structures.